I have one of those long 18mm AVI D engines, and I have one of their 24mm E's as well.
I still have several 27mm goofy diameter FSI F engines in F100 and F7 flavors, as well as some of those goofy diameter FSI D18/D20 and E6 angines.

I have a few old Composite Dynamics (Gary R's first foray into composites) 24mm E20's and 24mm F45?'s.
I actually flew an old Composite Dynamics 40 n-sec SU E20-7 that was date coled I think Jan. 1981 in an old beat-up Estes Maxi Alpha last year and the delay ACTUALLY WORKED nominally !!!

I have some tiny AVI 1/8 A engines that fit into an Estes BT-3 as well.

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When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !